So hey, just for my own personal playing I was messing around and I found a way to if you wanted to, have the pokemon between Celebi and Treecko in the game data able to be caught. Apparently if when using the GBA Game Editing Program use the Pokedex location editor and place all of them instead of from 387+ all to 0 for both national and local dex, you can trick the game into thinking when in the dex that they're all missingno and they'll no longer crash the game if you catch them when you didn't already have them.